The present application is directed to a method and system for alerting a mobile station coupled to a first network that a communication request for the station appears on a second network. More particularly, the present invention is directed to a method and system for tracking which network a mobile station is coupled to and then translating address information to communicate alert messages to the mobile station with regard to communications on yet another network.
It is known in the field of wireless communications to provide mobile terminal devices in accordance with a standard referred to as IS-136. In accordance with that standard the mobile terminal can have the capability of conducting communication on at least two different networks. One network is the standard wireless voice network while the other network is a packet data network commonly referred to as CDPD (Cellular Digital Packet Data).
An example of a known communication configuration is illustrated in FIG. 1. The mobile station 10 is capable of communicating over either one of two networks, a voice network 100 and a packet network 150. In voice network 100 the mobile station 10 can communicate with any one of a plurality of base stations (102a to 102n) depending on the cell in which the mobile station is located. The base stations are coupled to a mobile switching center (MSC) 101 which controls the switching for the wireless communications. The MSC 101 can be coupled to the public switch telephone network (PSTN). Typically, when the user of the mobile station turns on the station it will automatically register with the MSC 101 through the base station serving the cell in which the mobile station is located. The mobile station performs this registration through a digital control channel (DCCH) associated with the base station.
A mobile station 10 is also capable of packet data communication. These communications are handled via packet network 150. Packets symbolically represented as elements 151 are received by a mobile data intermediate system or mobile gateway (MDIS) 152 which in essence is a packet data counterpart to the MSC 101. The MDIS 152 can communicate with a plurality of mobile data base stations such as MDBS 153 which can send wireless transmissions to the mobile station 10 when that station is in the cell served by the MDBS. When the mobile station wishes to register for purposes of engaging in packet data communications, it does so over a packet control channel (PCCH) associated with the MDBS 153.
Presently, because of the different architecture of these two networks, the voice network and the packet network, there is a lack of commonality of interfaces. As a consequence, while the mobile station 10, is xe2x80x9ccamped onxe2x80x9d to the control channel for one of the two networks, (i.e., while it is set to communicate control information to or receive information from a base station relating to one of the control channels), it cannot receive any information from the other network. For example, if mobile station 10 is camped on to a DCCH, then any attempt at providing a packet data transmission or communication to mobile station 10 in the known network configuration, is impossible. There is no way to signal the mobile station 10 over the PCCH since the mobile station is locked onto or camped onto the DCCH. Similarly, should the mobile station be camped onto the packet network, PCCH in anticipation of packet data communication, it is unable to receive any notice of a communication via the voice network.
It is desirable to provide a system in which the mobile station, while active and camped on in one network, can receive notices of communications on another network with which it is capable of communicating.
In accordance with the present invention, the mobile switching center of the voice network and the MDIS of the packet data network can be in communication with one another either indirectly via a memory or directly. The indirect or direct communications operate to provide mobile station address information from the network on which the mobile station is camped to the alternative network. Then, alternative network, upon receipt of a communication request for the mobile station, can generate a request to the mobile station through the network on which it is camped to advise the mobile station of the existence of an attempted communication on the alternative network. This alert or notice can be generated directly by the alternative network which could use an address translator to identify the address of the mobile station on the network on which it is camped and can create a message of appropriate structure for the network in which the mobile station is camped.
Alternatively, the network receiving the communication request could send a communication request trigger to the network to which the mobile station is camped and that latter network could generate the appropriate address and message alert for the mobile station.
The present invention permits the mobile station to receive notice of communication requests from the network or networks with which it has registered but on which it is not camped (that is, to which it has identified itself while its in the region of interest).